Film-trapdoor lock



Feb. 11, 1930. A. DINA 1,746,386

FILM TRAPDQOR LOCK` Original Filed Sept. 5, 1925 2 Sheets-Sheet 1INVENTOR Feb. 11, 1930.

A. DINA 1,746,386

FILM TRAPDOOR LOCK Original Filed Sept. 5, 1925 2 Sheets-Sheet 2|NvENToR ATTORNEY Patented Feb, 11, 1930 UNITED STATES PATENT OFFICEAUGUSTO DINA,YOF JERSEY CITY, NEW JERSEY, ASSIGNOR TO THE PRECISIONMACHINE CO., INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORKFILM-TRAPDOOR LOCK Application filed September 5, 1925, Serial No.54,618. Renewd 'June 27, 1929.

My invention relates to locking mechanisms for projectors.

'The improvement herein described pertains to a locking mechanismadapted particularly for use with the film trap door oi' a mot1on'objected to by the underwriters. In order to permit the threading in ofthe iilm into position for projection, the door must be moved' away fromwhat is known as the.

head. The door should thereafter be brought lightly against the film inits threaded position, one reasonjfor which is to hold the film fromvibrating and to reduce possible con` fiagration should the automatictire shutter v.fail tofall closed on ignition ot the iilm. The

ease with which-.the film may ignite, when passing through .theprojector, particularly in frontof the shutter, is well known to thoseskilledin the art. Failure of the lilm to move usually results incombustion of the film, due to the intense heat. Automatic closing ofthe re shutters is dependent upon this failure of movement of the film,but quite voften the mechanical connection therebetween fails to releasethese shutters when the iihn stops. I find, therefore, that it isessential to safety vto provide means which effectively minimizeconflagration 'of the film by holding the lilm against the head under apositive locking action. 1

Briefly, my invention comprises an improved form of locking mechanismfor a film trap door which is adapted positively to lock l the dooragainst the film when in position lfor projection, this lock beingcarried by an pawl carried by a thumb piece at the end of the axiallymovable rod serves to snap into position against the head at one side,to hold the rod extended with the door eectively held locked against thehead at the other` side. An improved mounting is provided for the springpressed pawl to compensate for any variation in the dimensions of themechanism to which the lock is applied. I wish to emphasize thesimplicity oi' the lock, its ability to be universally adapted and thequick and positive act-ion obtained thereby when moved to lockingposition.

In order to apprise those skilled'in the art how to practice andconstruct my invention, I shall now describe an embodiment thereof inconnection withv the accompanying drawings, whilch form a part hereo Inthe drawings Figure l is a front elevational View of that portion of theprojector which embodies my invention;

Fig. 2 is a side elevational view of the same, illustrating partly insection the film trap door lock, and further illustrating the manner ofreadily attaching it to the door;

Fig. 3 is a vertical sectional view through the locking)v mechanism,illustrating the film trap door held positively locked in closedposition; it

Fig. 4 is a slmilar view having the filmtrap door released; and

nis

Referring more particularly to the drawings, 10 is the frame or headcomprising thatA `portion of the projector which carries the automaticfire shutter 1-1. This shutter 1l is vertically slidable, in a wellknown manner, in guides 12 formed on a plate 13 secured to the abutmentor head l0. While it is not a' part of the present invention, it may bementioned that automatic releasing mechanism may be secured to thisshutter, so that when the film stops moving past the shutter opening.the shutter immediately falls into closed position. This is accomplishedby the links 14 and l5 beingr connected in a manner to lallow shutter 11to drop closed when .the motion ofthe film is stopped.

Fig. 5 is a top vi^w of the locking mechato receive a bearing 18 may beformed on head 10 adjacent to the door 16. A rod 19, to

which door 16 is fastened, passes centrally through bearing 18 and ispermitted to have axial non-rotative movement therein so as to allow thedoor to be brought against the head, as shown in Figs. 2 and 3. lThebearing 18 is enlarged at 20, in order to vseat snugly`in hub 17, andhas an annular shoulder 21 thereon, preferably to space the door 16 fromhead 10, this space being provided for the film when threaded in theprojector. The opposite end of bearing 18 may be reduced, as indicatedat 22, to provide an `annular groove V23 between the bearing andthe hub.However, the central opening of the lhub may be slightly larger at thispoint to insure the proper size annular groove 23.

The end of the rod 19 is internally threaded to receive a threaded stud24. The threaded stud 24 is an extensionl of the member 26 and is formedwitha collar 27. A thumb piece 28 ismounted upon and embraces the member26 between the outer end of the latter and said collar 27, the collarserving as an abutment at one end for the thumb piece, while at theopposite end a cap nut 3() is threaded on the member 26 for preventingdisplacement of the thumb piece.

A pair of downwardly extending integral lugs' 32 may be furnished on thelowerv side of thumbpiece 28, these lugs being spaced apart to receivetherebetween a spring pressed pivotally mounted pawl 33. A pin 35threaded' inat one side of these lugs, as shown in Fig. 1, serves as themounting for pawl 33. A pocket 34 may be formed in the bottom of thumbpiece 28 for the reception of one end of a compressionspring 36. Theopposite end of this spring seats in a similar pocket 37 inthe pawl 33.The function of pawl 33 is to lock door 16 closed, as shown in Fig. 3,yby having its inner end engage against the hub 17 as indicated at X inthis Figure. That is to say, when the thumb piece 28 is engaged andpulled outwardly, the spring 36 presses the outer end of the pawl 33downwardly in order to drop its inner end in front of thehub 17 forengagement therewith. A

.Y sleeve 38 is threaded upon the stud 24 and is brought tightly againstcollar 27. The lockv ing pawl 33 presses against said sleeve and isretained thereby in the' plane of hub 17. The locking pawl 33 iseccentrically adjustable on, that is, is loosely engaged with itsfulcrum to compensate for any variation in the dimensions of themechanism to which the lock is applied, say in the dimensions of the dorand head, or in the size of the hub and ro To openthe door4 16, thelocking pawl 33 must be released by pulling upwardly on the outer end ofthe pawl against the tension of spring 36. This brings the locking pawlaway from hub 17 at X to permit the rod to slide axially in the head andto move the door. to open position. It will be noted that the outersurface of hub 17 is tapered slightly for allowing the pawl- 33 totravel thereover, when the latter is released, and that the sleeve 38`moves into the annular groove 23.

From the foregoing description, it will be observed that the door isheld positively locked against the head by virtue of the locking pawl 33falling in front of the hub 17 and locking. Accidental release of thelock is difficult and is in fact prevented due to the spring 36 tendingto hold the pawl pressed against the sleeve 38 and hub 17, and further,to the fact that this hub is provided with a tapered exterior surfaceover which the pawl must travel to open the door, and, as will be hereseen, this movement must be accomplished with a positive force or anintentional release of the pawl.

It will be further observed that the locking mechanism, hereindisclosed, is in the novel form of an interchangeable attachment, thatis, the hub 17 and rod 19 are so constructed as to receive a standarddoor knob, if so desired. The manner of readily removing the lockingmechanism has been clearly illustrated in Fig. 2. The ease of pullingthe door to closed position, as well as the sure and ositive -action ofthe locking pawl 33 in loc ing position in front of the hub areimportant advantages of my invention. Once in this position it requiresintentional release for the locking pawl 33 to move outwardly againstthe action of spring 36.

thereby positively locking said door in closed position against saidhead.

2. In combination, a head, a door, and mechanism for positively lockingsaid door in closed position against said head, said mechanismcomprising a member having sub stantially axial movement in saidlheadconnected at one endto said door, and a locking element carried atthe other end of said member tending normally to drop in front of saidholding said door against said head, said locking mechanism including areleasable element having means tending to move it into a positionagainst said head restraining the axial movement of said member.

4. In combination, a head, a door adapted to be positively locked inclosed position when moved against said head, mechanism for locking saiddoor closed, said mechanism comprising a movable member extendingthrough said head and a spring pressed pawl mounted on said member, saidpawl adapted to snap into position against said head to prevent themovement of said member and thereby lock said door closed.

5. In combination, a head, a door adapted to be locked in closedposition against said "head, means for movingsaid door to closedposition and for locking the same therein, said means includin anaxially movable rod connecting to sai door and extending through saidhead, and a spring pressed-pawl pivotally mounted on said rod adaptedautomatically to snap into position against said head for preventingaxial-movement of said rod when said door is moved to closed 'positionagainst said head by said rod.

` 6. In a locking mechanism for a film trap door, the combination ofahead, means for moving said door to closed position against said head,said means comprising a movable rod seated in said head and connected tosaid door, and a locking pawl at the outer end of said rod forpositively locking said door in closed position against said head.

7. In a locking mechanism for a film trap door, the combination of ahead, means forv moving said door to closed position against said head,said means comprising a movable rod seated in said head and connected tosaid door, and a locking pawl at the outer end of said rod forpositively locking said door in closed position against said head, saidpawl .servingautomatically to drop in front of said head to preventinward movement of said rod.

V8. In a locking mechanism for a film trap door, the combination of ahead, means for moving said door to closed position against said head,said means comprising a movable rod extending within said head andconnect- 'ing to said door, agripping element on the outer end of saidrod, and a latching element carried adjacent said gripping element fordropping into latching position against said head when said rod is movedoutwardly from said head to close said door.

9. In a locking mechanism for a film trap door, and detachably mountedlocking mechanism at the outer end of said rod forpositively lockingsaid door in closed position.

10. In a locking mechanism for a film trap door, the combination of ahead, a rod extending through said head for moving said door to closedposition, an outwardly extending hub on said head through which said rodprojects, and locking mechanism for preventing the movement of said rodin said head, said lmechanism comprising a locking device adapted todrop in front of said hub.

11. In a locking mechanism for a film trap door, the combination of ahead, a rod extending through said head for moving said door to closedposition, a hub on said head through which said rod'projects, and alocking pawl carried by said rod adapted to drop in front of said hubfor preventing the movement of said rod in said head when said door isin closed position.l

12. In a locking mechanism for a film trap door, the combination of ahead, a rod extending through said head for moving said door to closedposition, a hub on said head through which said rod projects, and aspring pressed pivotally mounted pawl at the outer end of said rodadapted to drop in front of said hub for preventing the movement offnecting to said door and movably extending through said head, and meansfor positively locking said door against said head, said nieansincluding a pivotally mounted pawl disposed at the outer end of said rodadapted to drop in front of said head to prevent inward movement of saidrod, said pawl being eccentrically adjustable at its pivotal mounting tocompensate for variations in the dimensions of the parts of saidmechanism.

14. In combination with a film trap door adapted to move to closedposition against a head, and a rod connecting to said door and movablyextending through `said head, of locking mechanism for said door adaptedpositively to lock said door in closed position comprising a handledetachably connected to the outer end of said rod, and a spring pressedpawl arranged on said handle to lock said rod against inward movement.

15. In a device of the character described, an abutment and a trap doormovable relatively thereto, means for moving said door connected theretoand extending to the opposite side of said abutment, a hub memberythrough which said means is movable, and

ymeans carried by said first mentioned means and positively engagingsaidhub to positively lock the doorin one of its positions.

16. In a device of the character described, 5 in combination, a, lm gatefor a motion picture projector and a door adapted to be movedagainstsaid gate, of a rigid member supporting said door and passingthrough andfslidable in said gate, said rigid member having a'detachable handle portion on. the end thereof opposite to said portion,a pawl member pivotally mounted on said handle, a hubmember surroundingsaid rigid member and projecting from said film gate and disposed in apath to be engaged by said paWl Vwhen said handle is in a predeterminedposition.

In testimonyy whereof, I have hereunto signed my name. 2o AUGUSTO QINA.

